The objective of this research is to determine the chemical nature of antineoplastic components associated with macromolecular fractions from marine invertebrate with an ultimate goal to develop unique antitumor drugs. Specifically it is intended to obtain unequivocally pure active components and to determine if the activity is inherent to the large molecules. Secondly the structures of the active compounds will be established in order to find the common structural features such as types and sequence of sugars. Thirdly elucidation of the nature and origin of capricious antitumor activity observed in shellfish will be done. This proposal is based on our recent findings of promising antitumor substances in the Atlantic sea scallop, Placopecten magellanicus, and other marine invertebrates, but is also intended to clarify the ambiguity surrounding the reported antitumor compounds in clams: "mercenene" and "paolin".